The content of 238Pu, 239Pu and 241Am in the liver and skeleton was estimated from radiochemical analysis of human liver and bone samples obtained at autopsy from former actinide workers whose occupational histories were suggestive of chronic inhalation exposures, with minor skin contamination and wounds documented in a few individuals. For times estimated to be several years to a few decades post intake, 75.8 +/- 15.3% of the total 241Am in the skeleton and liver was found in the skeleton (25 cases) as compared with 63.4 +/- 24.1% for 238Pu (36 cases) and 53.2 +/- 18.2% for 239Pu (43 cases). These differences are significant at the 95% confidence level. Of these cases, 34 included data on both 238Pu and 239Pu and were divided into high and low activity subgroups. The difference in the fractionation of the two Pu isotopes was apparent only in the low activity subgroup, suggesting that the difference observed between the Pu isotopes may be an artifact of the data. The different partitioning of these three nuclides suggests that the ALIs for 238Pu and 241Am may be high by about 25-50% if only the dose to bone is considered and may be high by 12-13%, based on the weighted committed dose equivalent in target organs or tissues.

Urinalysis measurements from 31 workers acutely exposed to uranium hexafluoride (UF6) and its hydrolysis product UO2F2 (during the 1986 Gore, Oklahoma UF6-release accident) were used to develop a modified recycling biokinetic model for soluble U compounds. The model is expressed as a five-compartment exponential equation: yu(t) = 0.086e-2.77t + 0.0048e-0.116t + 0.00069e-0.0267t + 0.00017 e-0.00231t + 2.5 x 10(-6) e-0.000187t, where yu(t) is the fractional daily urinary excretion and t is the time after intake, in days. The excretion constants of the five exponential compartments correspond to residence half-times of 0.25, 6, 26, 300, and 3,700 d in the lungs, kidneys, other soft tissues, and in two bone volume compartments, respectively. The modified recycling model was used to estimate intake amounts, the resulting committed effective dose equivalent, maximum kidney concentrations, and dose equivalent to bone surfaces, kidneys, and lungs.

The distribution of 239Pu in a human whole body is reported. The body contained 246 Bq of 239Pu of which 130 Bq (52.8%) was found in the lungs and associated lymph nodes. Of the remaining 116 Bq (47.2%) that constituted the systemic deposition, 51.2 Bq (44%) were in the skeleton, 48.6 Bq (42%) in the liver, and the remainder (14%) in the rest of the body exclusive of the lungs and associated lymph nodes. An unexpectedly high concentration was observed in the pituitary. The systemic distribution of Pu in this case, when combined with the exposure history, is suggestive of an initial partitioning ratio of 239Pu between skeleton and liver of less than unity, and a tentative initial distribution from the transfer compartment of 25% to the skeleton, 50% to the liver, and 25% to the rest of the body and early excretion is proposed for this case. Older biokinetic models, when used with the available urinalysis data for this case, typically overestimated the deposition when compared with the tissue analysis results, but more recent models provided estimates in close agreement with the autopsy results.

Urine bioassay ~easurements for uranium and medical laborato ry resu~ts were studied to determine whether there were any health effects from urcnium intake among a group of 31 workers exposed to uranium hexafluoride (UF6) and hydrolysis products following the accidental rupture of a 14-tun shipping cylinder in early 1986 at the Sequoyah FJels Corporation uranium conversion facility in Gore, Oklahoffid. Physiological indicators studied to detect kidney tissue damage inc "i uded tests for urinary protein, casts and cells, blood, specific gravity, and urine pH, blood urea nitrogen, and blood creatinine. We concluded after reviewing two years of follow-up medical data that none of the 31 workers sustained any observable health effects from exposure to uranium. The early excretion of uranium in urine showed more rapid systemic uptake of uranium from the lung than is assumed using the International Commission on Radiological Protection (ICRP) Publication 30 and Publication 54 models. The urinary excretion dota from these workers were USE" to develop an improved systemic recycling model for inhaled soluble uranium. We estimated initial intakes, clearance rates, kidney burdens, and resulting radiation doses to lungs, kidneys, and bone surfaces. Radiation dose limits and limits on intake, as recommended by the JCRP , were not exceeded. However, the NRC derived limit of 9.6 mg was exceeded by eight of the 31 workers. Maximum kidney concentrations in exposed workers ranged from 0.05 to 2.5 ~~ U/g kidney tissue. We found no toxicological effects on the kidneys of workers at these concentrations. Uranium urinalyses and medical laboratol'Y result s on Dlo od dnli lit' in c were studied to determine whether ~here were Jnv health eff ect s i n 3 1 \':orkcl's exposed to uranium hexafluoride (UF6) following-the acciden ta l r u~lu r e of d 14-ton shipping cylinde:r in early 1986 at a uranium convers io n facil ity in Gore, Oklahoma. The workers were likely exposed t o very hi gtl concent ' ,t(ia/;s of ai rborne uranium for short time periods. The mos t imp ort Jnt Sil()\'t •, t eli ll concern was inhalation of hydrofluoric acid (HF) with pos s ibl e l ung d lilldge and skin-exposure burns. The major long-term concern wa s kidney dd ll ldCJC in workers with significant intakes of uranium. Urinalyse s wet' e pe r forJ1!ed 0 11 workers to evaluate their health and kidney function. The data were also evaluated to estimate their initial intakes of ura~ium, resulting r adi ation doses to bone surfcces, kidneys, and lungs, and the resu It i ng (oIllmi tte d effective dose equivalent (a measure of risk to the whole body). ~he physiological indicators studied to detect kidney tissue damage by uranium poisoning included tests for urinary protein, casts and cells, urinary blood, specific gravity, pH of the urine, blood urea nitrogen, and blood creatinine. Physical examination and pulmonary function ' est res ults over a two-year follow-up period were also evaluated. We conclud ed fr om review of the medical records and laboratory results tha...

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